JP2002256098A - Polyester-based resin foam and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyester-based resin foam comprising a polyester copolymer as the base resin, excellent in biodegradability and hydrolysis resistance, having excellent mechanical properties such as compression and tensility. SOLUTION: This polyester-based resin foam comprises as a base material a polyester copolymer by >=50 wt.% comprising terephthalic acid component unit and adipic acid component unit and/or succinic acid component unit as the main dicarboxylic acid component unit, and having tensile modulus of <=100 MPa, and has an apparent density of 0.03 to 0.2 g/cm<3> and a thickness of 0.3 to 10 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester resin foam having excellent biodegradability and hydrolysis resistance and excellent mechanical properties such as compression and tension, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, polyethylene resin foam sheets have been widely used as cushioning packaging materials for home electric appliances and the like. However, although the polyethylene resin foam sheet is excellent in flexibility and cushioning property, it is often used by being reinforced by laminating a resin film or the like because of insufficient tensile properties. Further, since most uses of the polyethylene resin foam sheet are disposable, in recent years, biodegradability has been demanded for disposable plastic packaging materials as an environmental problem.

Accordingly, Japanese Patent Application Laid-Open No.
No. 2572 discloses an extruded foam sheet made of an aliphatic polyester resin having a specific melt viscosity and melt tension. However, the biodegradable foam sheet disclosed in the publication has a lower tensile elongation, a higher elastic modulus and a lower flexibility than the polyethylene resin foam sheet. Due to such a thing, even if the home appliance is packaged, the cushioning wrapping material may have poor conformability to the shape of the home appliance, may cause a crack immediately, or may damage the surface of the packaged object. Was not satisfactory enough.

[0004] Also, polyethylene resin foam boards and polyethylene resin rod-like foams have been conventionally used as cushioning wrapping materials and the like, but those having biodegradability have not been commercialized. Mechanical properties such as compression are inferior to expensive urethane foams, and new applications are expected by further improving the mechanical properties. Although it is possible to obtain a biodegradable foamed board by the technique described in JP-A-10-152572, the mechanical properties such as compression are insufficient as in the case of the polyethylene resin foamed board. Was.

On the other hand, Japanese Patent Publication No. 10-505620 discloses a biodegradable polyester copolymer of an aromatic polycarboxylic acid, an aliphatic polycarboxylic acid and a polyol.
This publication describes the use of the polyester copolymer as a material for a foamed member. In addition, Tokio Table 1
Japanese Patent Publication No. 0-508640 describes a biodegradable polyester copolymer having a branched structure of adipic acid, terephthalic acid and C2 to C6-alkanediol. There is a description of its use in manufacturing.

[0006] However, although the above publication describes that the biodegradable polyester copolymer can be used for producing a foam, there is no specific example of the foam.
It is unclear whether a practically usable foam can be obtained or not, leaving room for intensive research.

[0007]

DISCLOSURE OF THE INVENTION The present invention relates to a polyester comprising a polyester copolymer as a base resin and having excellent biodegradability and hydrolysis resistance and excellent mechanical properties such as compression and tension. It is an object of the present invention to provide a resin foam and a method for producing the same.

[0008]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have completed the present invention. That is, the polyester resin foam of the present invention contains 50% by weight or more of a polyester copolymer containing a terephthalic acid component unit and an adipic acid component unit and / or a succinic acid component unit as main dicarboxylic acid component units, It is a polyester resin foam (A) having an apparent density of 0.03 to 0.2 g / cm ³ and a thickness of 0.3 to 10 mm made of a base resin having a tensile modulus of 100 MPa or less.

Further, the polyester resin foam of the present invention contains 50% by weight of a polyester copolymer containing terephthalic acid component units and adipic acid component units and / or succinic acid component units as main dicarboxylic acid component units. A polyester resin foam (B) containing a base resin having a tensile modulus of 100 MPa or less, an apparent density of 0.035 to 0.25 g / cm ³ , and a cross-sectional area perpendicular to the extrusion direction of 5 cm ² or more. is there.

Further, the method for producing the polyester resin foams (A) and (B) of the present invention comprises the steps of: (a) preparing a terephthalic acid component unit, and (b) an adipic acid component unit and / or a succinic acid component unit. Containing 50% by weight or more of a polyester copolymer containing, the equilibrium compliance (J ₀ ) determined by dynamic viscoelasticity measurement is 1.8 × 1
0 ^-4 Pa ^-1 or higher, the tensile and the resin elastic modulus is less than 100 MPa, and a blowing agent comprising a physical blowing agent, kneaded to a foaming molten resin in an extruder, a low pressure the molten resin from the high pressure zone It is characterized by being extruded into a region and foamed.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The polyester resin foam of the present invention comprises (i) a terephthalic acid component unit and (ii) an adipic acid component unit as main dicarboxylic acid component units.
Alternatively, a polyester copolymer containing a succinic acid component unit is used as the base resin.

The polyester copolymer used in the present invention is produced by a method of polycondensing a dicarboxylic acid component and a diol component, a transesterification reaction of a polyester homopolymer and / or a polyester copolymer, or the like. The dicarboxylic acid component and the diol component of the polyester copolymer used in the present invention will be described in detail. As the dicarboxylic acid component, dicarboxylic acid or an ester-forming derivative thereof can be used. Examples of the ester-forming derivatives include ester derivatives such as dimethyl ester and diethyl ester, salts such as diammonium salts, and acid halides such as dichloride.

In the polyester copolymer, the main dicarboxylic acid component units are (i) a terephthalic acid component unit and (ii) an adipic acid component unit and / or a succinic acid component unit, and the molar ratio is 20: 80-50: 5
0 is preferable, and further, a material having a lower density and a higher thickness is obtained, and the biodegradability is excellent.
70-45: 55 is more preferred. The molar ratio is 20: 8
In addition to those having a ratio of 0 to 50:50, there is a possibility that desired physical properties or biodegradability cannot be obtained. The meaning that the main dicarboxylic acid component unit is (i) a terephthalic acid component unit and (ii) an adipic acid component unit and / or a succinic acid component unit means that (i) a terephthalic acid component unit; In addition to the adipic acid component unit and / or the succinic acid component unit, (iii) 30 other dicarboxylic acid component units
mol% or less, preferably 20 mol% or less. Other dicarboxylic acid component units include phthalic acid, isophthalic acid, 4,4′-
Diphenyldicarboxylic acid, 3,4′-diphenyldicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalene Aromatic dicarboxylic acids such as dicarboxylic acids or anhydrides thereof, or component units derived from ester-forming derivatives thereof, or glutaric acid, pimelic acid,
Aliphatic dicarboxylic acids or anhydrides such as suberic acid, azelaic acid, sebacic acid, dodecandioic acid, etc.
Or a component unit derived from an ester-forming derivative thereof, or 1,4-cyclohexanedicarboxylic acid,
Component units derived from an alicyclic dicarboxylic acid such as 1,3-cyclohexanedicarboxylic acid, decalindicarboxylic acid, tetralindicarboxylic acid, or an anhydride thereof, or an ester-forming derivative thereof can be exemplified.

On the other hand, diol component units include ethylene glycol, propylene glycol, trimethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol and 1,4-butanediol. , A component unit derived from an aliphatic diol such as 1,5-pentadiol, 1,6-hexanediol, or 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,6-cyclohexanediol And the like, and component units derived from an aromatic diol such as bisphenol A, among which ethylene glycol, 1,2
-Propanediol, 1,3-propanediol, 1,
Component units derived from 2-butanediol and 1,4-butanediol are preferred. In particular, the main diol component unit is preferably a butanediol component unit. In addition, the meaning that the main diol component unit is a butanediol component unit means that, in addition to the butanediol component unit, other diol component units are 30 mol% or less,
It preferably means that it may be contained at 20 mol% or less.

Further, the above-mentioned polyester copolymer has its molecular terminals sealed with a small amount of a component unit derived from a monofunctional compound such as benzoic acid, benzoylbenzoic acid, benzyloxybenzoic acid, methoxypolyethylene glycol and the like. It may be. Also, trimellitic acid,
It may contain a small amount of a component unit derived from a polyfunctional compound such as pyromellitic acid, trimesic acid, glycerin, pentaerythritol and the like. Further, the polyester copolymer used in the present invention can be various modified products. As such modified products, hitherto known ones, for example, Japanese Patent Publication No. 10-508640 and Japanese Patent Publication No. 10-508
No. 645, Tokiohei 10-508647, Tokiohei 10-
No. 512006, No. 11-500761, No. 11-511767, No. 11-500762,
Tokuhyo Hei 11-500157, Tokuhyo 2000-5043
Modified products described in each gazette such as No. 55 can be mentioned.

The polyester resin foam of the present invention (A)
And (B) melt the polyester copolymer, preferably under high temperature and pressure, mix the melt with a blowing agent,
It is obtained by extrusion foaming in the low pressure zone. Examples of the blowing agent include an inert gas, a saturated aliphatic hydrocarbon, a saturated alicyclic hydrocarbon, an aromatic hydrocarbon, a halogenated hydrocarbon, an ether, a ketone, and the like, and these are used alone or in combination of two or more. . Specifically, carbon dioxide, nitrogen, methane,
Ethane, normal butane, isobutane, normal pentane, isopentane, neopentane, normal hexane,
2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, methylcyclopropane, cyclopentane, 1,1-dimethylcyclopropane, cyclohexane, methylcyclopentane, ethylcyclobutane, 1, 1,2-trimethylcyclopropane, benzene, 1,1,1,2-tetrafluoroethane, 1,1-zirfluoroethane, 1,1,1,2,2
-Pentafluoroethane, trichlorotrifluoroethylene, dichlorotetrafluoroethylene, dimethyl ether, 2-ethoxyethanol, acetone, ethyl methyl ketone, acetylacetone and the like. Further, a chemical foaming agent can be used as the foaming agent. Examples of such a chemical foaming agent include azodicarbonamide, dinitrosopentamethylenetetramine, azobisisobutyronitrile, and sodium bicarbonate. These foaming agents can be appropriately mixed and used. The amount of the foaming agent used varies depending on the type of the foaming agent, the desired expansion ratio of the foam, and the like. However, the guideline for the amount of the foaming agent used is 1 kg of the base resin in the case of an organic physical foaming agent such as normal butane. Is used in an amount of 0.05 to 3 mol. If the amount of the foaming agent is less than 0.05 mol, there is no cost advantage due to low foaming, and only a foam having poor heat insulating properties can be obtained. If the amount exceeds 3 mol, gas sealing with a die becomes unstable and good. There is a possibility that a suitable foam may not be obtained. As the foaming agent used in the present invention, a physical foaming agent, in particular, a foaming agent containing an organic physical foaming agent such as a saturated aliphatic hydrocarbon, a saturated alicyclic hydrocarbon, an aromatic hydrocarbon, or a halogenated hydrocarbon is used. Is preferable because a good foam having a small apparent density can be efficiently obtained.Furthermore, as the organic physical foaming agent, saturated aliphatic hydrocarbons and halogenated hydrocarbons are preferable, and particularly, normal butane and And / or isobutane is preferred. The content of the organic physical foaming agent in the foaming agent containing the organic physical foaming agent is such that the organic physical foaming agent is 50 to 1 with respect to 100% by weight of the total amount of the foaming agent.
It is preferably 00% by weight.

In the foams (A) and (B) of the present invention, not only the above-mentioned polyester copolymer is used alone, but also polybutylene succinate, polyethylene succinate, polybutylene succinate adipate, polycaprolactone One or more biodegradable resins such as polylactic acid, polybutylene succinate carbonate, polyhydroxybutyrate, polyvinyl alcohol, and cellulose acetate can be used. in this case,
The biodegradable resin is 100% by weight of the resin constituting the foam.
Is preferably mixed at a ratio of less than 40% by weight.

The foams (A) and (B) of the present invention contain 50% by weight of the above polyester copolymer and have an equilibrium compliance (J ₀ ) of 1.8 × 10 in dynamic viscoelasticity measurement.
^-4 Pa ^-1 or more, preferably 2.0 × 10 ^{-4 to} 1.5 × 1
It is obtained by extruding and foaming a resin having 0 ^-3 Pa ^-1 and a tensile modulus of 100 MPa or less, preferably 20 to 80 MPa.

If the tensile modulus of the resin exceeds 100 MPa, the physical properties relating to the rubber-like elasticity specific to the foam of the present invention will be insufficient.

In the present specification, the tensile modulus is J
It is measured according to IS K7113 (1995). However, the shape of the test piece was a No. 2 type test piece (1.1 mm thick) described in JIS K7113 (1995), and the test speed was 5
0 mm / min. The test piece was pressed by a hot press heated to 230 ° C. so as to have a thickness of 1.1 mm using a jig and press-formed for 5 minutes to obtain a thickness of 1.1 mm.
It is assumed that a resin plate having a thickness of 2 mm is processed into a predetermined test piece shape, and the condition is adjusted for 48 hours or more at a temperature of 23 ° C. and a relative humidity of 50%. Depending on the type of resin, air bubbles may be included in the obtained resin plate due to water absorption of the resin at the time of hot pressing for preparing the resin plate, but in such a case, the resin is placed in a vacuum oven at 150 ° C. Using a sufficiently dried resin such as drying for 10 hours, a resin plate containing no air bubbles is prepared again to obtain a test piece.

The equilibrium compliance of the resin (J
_{When 0} ) is less than 1.8 × 10 ⁻⁴ Pa ⁻¹ , the foamability is insufficient, and although the foam is obtained, it is difficult to control the apparent density and thickness of the foam according to the purpose, The appearance may be unsatisfactory.

On the other hand, when the equilibrium compliance (J ₀ ) exceeds 1.5 × 10 ⁻³ Pa ⁻¹ , it may be difficult to obtain a material having a small apparent density, and it may be difficult to obtain a plate-like or rod-like material. When a foam having a large area is obtained, it is necessary to sufficiently consider curing conditions in consideration of dimensional stability such as shrinkage of the molded body after extrusion foaming. Terms of high foaming, that open cell ratio of the foam obtained is reduced, cushioning their associated, J ₀ of the resin from the viewpoint of improvement of such compressive strength 2.
It is preferably set to 0 × 10 ^{−4 to} 1.5 × 10 ⁻³ Pa ⁻¹ .

In the present specification, the equilibrium compliance (J ₀ ) is measured by a dynamic viscoelasticity measuring machine (Dynamic Analyzer SR200 manufactured by Rheometrics Scientific F.E.).

The measurement of the equilibrium compliance (J ₀ )
Specifically, it is performed as follows. First, a resin having a diameter of 2 mm was obtained from a sample resin plate for measurement having a thickness of about 2 mm obtained by press-molding a resin with a hot press at a temperature of 230 ° C. for 5 minutes.
Prepare a 5 mm disc sample. Next, this sample was sandwiched between 25 mm diameter parallel plates of a dynamic viscoelasticity measuring apparatus, heated to 190 ° C., and left under a nitrogen atmosphere for about 10 minutes, and then the interval between the parallel plates was set to 1.4.
mm, and remove the molten resin protruding from the parallel plate. Then, the upper parallel plate is rotated so that a constant stress σc of 100 Pa is applied to the sample melted in the nitrogen atmosphere, and the time lapse of the amount of strain γ (t) based on the time t = 0 when the constant stress σc is started to be applied. Measure the change. The amount of strain γ (t) sharply increases at first, but gradually increases with time, and changes linearly with time after a sufficient time has elapsed. The apparatus settings of the dynamic analyzer SR200 are set as shown in Table 1, and the equilibrium compliance (J ₀ ) is calculated by an automatic function on the apparatus.

[0025]

[Table 1]

The value obtained by dividing the above strain γ (t) by the constant stress σc is called creep compliance J (t) and is defined by the following equation (1).

J (t) = γ (t) / σc (1)

The creep compliance J (t) suddenly increases at the beginning like the strain amount γ (t), but gradually increases with time, and changes linearly with time after a sufficient time has elapsed. (Shown in FIG. 1). The creep compliance J that changes linearly
(T) can be represented by the following equation (2).

J (t) = J ₀ + t / η (2)

The equilibrium compliance (J ₀ ) in this specification is given as J ₀ in the above equation (2). That is, in a diagram in which the creep compliance J (t) is plotted on the vertical axis and the time t is plotted on the horizontal axis, the intercept at the time t = 0 when the linear part of the creep compliance J (t) is extrapolated to the time t = 0. Given as

The resin containing the polyester copolymer used in the present invention and having a specific tensile elastic modulus and a specific equilibrium compliance (J ₀ ) at 190 ° C. includes, for example,
It can be prepared by changing the molar ratio of the terephthalic acid component unit to the adipic acid component unit of the dicarboxylic acid component unit of the polyester copolymer contained in the resin in an amount of 50% by weight or more. Equilibrium compliance can be achieved by introducing the above polyfunctional compound into the polyester copolymer, introducing an ether bond, or introducing a micro-crosslinked structure that does not generate a gel due to electron beam irradiation, organic peroxide, or the like. Indicates the target value. However, in the present invention, the method for synthesizing, modifying, and adjusting the properties of the resin constituting the foam are not particularly limited. Specific examples of the resin satisfying the equilibrium compliance and the tensile modulus specified in the present invention include polyethylene terephthalate adipate “Ecoflex FBX7011” manufactured by BSF.
(The molar ratio of the terephthalic acid component unit to the adipic acid component unit is 42:58). In addition, it is preferable that the said polyester copolymer used by this invention contains 70 weight%-100 weight% in resin which comprises a foam. When the resin constituting the foam is composed of 100% by weight of the polyester copolymer, the polyester copolymer has a specific equilibrium compliance (J ₀ ) and a specific tensile modulus. There must be.

The foams (A) and (B) of the present invention can be obtained by extrusion foaming the above resin. As the extrusion foaming method, for example, after heating and kneading the above-mentioned base resin in an extruder, further injecting and kneading a physical foaming agent under high temperature and high pressure to form a foamable molten resin composition, Extruded under atmospheric pressure through an annular die provided to foam into a cylinder, and cut this tubular foam along the extrusion direction to form a foam sheet, extruded under atmospheric pressure through an annular die into a cylindrical shape Foaming, pressing the cylindrical foam with a roll, bonding the inner surfaces of the cylindrical foam to each other to form a plate foam, extruding the foamable molten resin composition through a flat die, and forming the plate foam. And a method in which the foamable molten resin composition is extruded through a deformed die to give various foams having different cross-sectional shapes.

If necessary, an accumulator may be provided between the extruder and the die. By installing an accumulator, the discharge speed can be dramatically increased, so that even a small extruder, the foam of the present invention having a high expansion ratio and a high thickness, especially a plate-like or long-form foam Suitable for gaining body.

In the production of the foams (A) and (B) of the present invention, an air conditioner may be added to the base resin as required. Examples of the foam control agent include inorganic powders such as talc and silica, acidic salts of polyvalent carboxylic acids, and reaction mixtures of polyvalent carboxylic acids with sodium carbonate or sodium bicarbonate. The added amount of the air bubble adjuster is base resin 1.
It is preferably at most 3 parts by weight per 00 parts by weight.

If necessary, the base resin may contain an amount of an anti-shrinking agent, an antistatic agent, a weathering agent in an amount not to impair the intended purpose,
Various additives such as a lubricant, an antioxidant, and a coloring agent may be blended. Furthermore, talc, silica, calcium carbonate,
Clay, zeolite, alumina, barium sulfate and the like can be added as an inorganic filler. The addition amount of these inorganic fillers is 40% of the total weight of the resin and other additives.
It is preferable that the upper limit be weight%. The inorganic filler preferably has an average particle size of 1 to 70 μm. When the inorganic filler is added, the heat resistance of the obtained foam is improved, and the calorie burned when the foam is incinerated can be further reduced.

Hereinafter, the foams (A) and (B) of the present invention will be described in more detail. (Foam (A)) The apparent density is 0.03-0.2.
g / cm ³ , preferably 0.04 to 0.12 g / cm ³
cm ³ . If an attempt is made to obtain a foam having an apparent density of less than 0.03 g / cm ³ , shrinkage or the like occurs, and a good foam cannot be obtained. In addition, the mechanical properties are too low and cannot be tolerated in practical use. The apparent density is 0.2g
If it exceeds / cm ³ , the feel of the foam becomes hard, and the cushioning property may be insufficient depending on the application. Its thickness is 0.3 to 10 mm, preferably 0.5 to 7 m
m. If the thickness is less than 0.3 mm, the cushioning property and the strength are too low, so that it cannot be used in practical use.
On the other hand, if the thickness exceeds 10 mm, it must be manufactured by a device with a special structure in which a continuous forming tool is attached to the downstream side of the flat die. 10m thick by die
Even if a material having a size exceeding m is obtained, distortion such as a mandrel curl tends to remain, which makes it difficult to use it as, for example, a packaging material. The tensile elongation of the foam (A) is 2
It is at least 00%, preferably 300 to 900%. If the tensile elongation is less than 200%, the ability to follow the shape of the material to be packaged is poor, so that the package cannot be firmly packed, and cracks are likely to occur at corners and sharp parts of the material to be packaged. Note that the tensile elongation of the foam (A) is determined in the width direction (T) perpendicular to the extrusion direction (MD) of the foam and the extrusion direction of the foam.
At least one of the values of D) may be within the above range, but it is more preferable that both the MD and TD values are within the above range. The tensile modulus of the foam (A) is 1 to 30 MPa, preferably 1 to 5 MPa. If the tensile modulus is less than 1 MPa, bottoming or the like may occur even with a small load, and the cushioning property may be insufficient. The tensile modulus of the foam (A) is such that at least one of the values in the extrusion direction (MD) of the foam and the width direction (TD) orthogonal to the extrusion direction of the foam is within the above range. However, it is more preferable that the values of MD and TD both fall within the above ranges. The average cell diameter of the foam (A) is preferably 0.2 to 2.5 mm, and more preferably 0.3 to 2.0 mm. The average cell diameter of the foam is 0.
If it is less than 2 mm, the cells communicate with each other during the production of the foam, causing shrinkage and the like, and it is difficult to obtain a good foam. Moreover, even if it is obtained, there is a possibility that the corrugate is generated tightly and becomes difficult to handle. On the other hand, if the average cell diameter exceeds 2.5 mm, the cell membrane becomes thick, giving a feeling of lack of flexibility, and the appearance may be deteriorated. The open cell rate of the foam (A) is preferably 0 to 70%, more preferably 0 to 60%, and particularly preferably 0 to 40%. When the open cell ratio exceeds 70%, the flexibility increases, but the compressive strength decreases.
There is a possibility that bottoming will occur. The foam (A) can be subjected to heat molding using a mold such as a tray. (Foam (B)) The apparent density of the polyester resin foam (B) of the present invention is 0.035 to 0.25 g / cm.
³ , preferably 0.04 to 0.20 g / cm ³ . If the density is less than 0.035 g / cm ³ , it is difficult to produce a foam having uniform cells, and the foam has a high open cell ratio and shrinks, so that a good foam cannot be obtained. . On the other hand, if it exceeds 0.25 g / cm ³ , heat insulation and lightness are insufficient. Foam (B)
The area of the cross section perpendicular to the extrusion direction is 5 cm ² or more. If it is less than 5 cm ² , the production efficiency is poor, and the applications for use are limited. Although the upper limit of the area is not particularly limited, it is usually about 5000 cm ² .
The thickness of the foam (B) is 0.5 cm or more, and further 1 cm.
The above is preferred. The compressive strength of the foam (B) in the thickness direction (ZD) is preferably 1 to 50 kPa, more preferably 5 to 35 kPa. When the compression strength is less than 1 kPa, the compression strength is too low, and depending on the application, the deformation of the foam may be too large. On the other hand, 50 kPa
If it exceeds, the compressive strength is too high, and the flexibility may be poor depending on the application. In other words, a foam in the range of 1 to 50 kPa hardly bottoms out and becomes a flexible foam. Further, the compression modulus in the thickness direction (ZD) of the foam (B) is preferably 0.1 to 6 kPa, more preferably 0.5 to 4 kPa. Compression modulus is 0.1kPa
If it is less than 6 kP, it may be too soft for practical use.
When it exceeds a, it becomes practically hard. That is,
A foam in the range of 0.1 to 6 kPa is a moderately soft foam having a unique feel not found in the conventional foam. The average cell diameter of the foam (B) is preferably 0.2 to 5 mm. If it is less than 0.2 mm, shrinkage or the like may occur during the production of the foam, and a good foam may not be obtained. If it exceeds 5 mm, the bubble film may be too thick, resulting in poor appearance and poor flexibility. The open cell ratio of the foam (B) is preferably from 0 to 70 from the viewpoint that mechanical properties such as moderately high compressive strength are obtained.
%, More preferably 0 to 60%, particularly preferably 0 to 40%. On the other hand, for applications in which mechanical properties such as compressive strength are not so required, the open cell ratio exceeds 70% in order to sufficiently exhibit physical properties related to the rubber-like elasticity of the foam of the present invention and to also have flexibility. Preferably,

[0035]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples.

Melting of resin used in each of Examples and Reference Examples
The characteristics and the like are described below. (1) Base resin of Examples 1 to 8 Ecoflex FBX7011 manufactured by BASF (molar ratio of terephthalic acid component unit to adipic acid component unit: 42:58) Melt index (MI) (190 ° C., 2.16 kgf) 5.6 g / 10 min ・ Melt tension (190 ° C.) 0.8 gf ・ Melting point (Tm) (JIS K7121) 116 ° C. ・ Density 1.25 g / cm^Three  ・ J₀ 2.45 × 10^-FourPa^-1  -Tensile modulus 53 MPa (2) Base resin of Reference Examples 1 and 3 Bionole # 1903 manufactured by Showa Polymer Co., Ltd. MI (190 ° C, 2.16 kgf) 3.6 g / 10 min Melt tension (190 ° C) 5 0.6gf ・ Tm (JIS K7121) 112 ℃ ・ Density 1.26g / cm^Three  (3) Base resin of Reference Example 2 Low density polyethylene DFDJ6775 manufactured by Nippon Unicar Ltd. MI (190 ° C., 2.16 kgf) 0.2 g / 10 min Melt tension (190 ° C.) 18.0 gf Tm (JIS K7121) 110 ° C · Density 0.92g / cm^Three 

Examples 1 and 2 and Reference Examples 1 and 2 The above-mentioned base resin and talc as a cell nucleating agent were charged into a first extruder, kneaded by heating and melted, and isobutane / normal butane = 3/7 as a blowing agent. (Weight ratio) of the mixture is pressed into an extruder and further kneaded to obtain a foamable molten resin. Next, the foamable molten resin is cooled to a predetermined resin temperature by a second extruder connected by a crossbar, and is extruded and foamed in a cylindrical shape into the atmosphere from an annular die attached to the extruder tip, and this is put on a mandrel. After taking out and cooling and solidifying, a cylindrical foam was cut out at one place to obtain a sheet-like foam. The amount of the foaming agent added, the amount of talc added, and the resin temperature during extrusion foaming are as shown in Table 2. In Examples 1 and 2, the obtained foam was heated and vacuum-formed to obtain a 150 mm
× 120mm depth 30mm (bottom 115mm × 95m
m) A good tray free of burns and shaping defects was obtained. As the thermoforming conditions, a single-shot FE-36 molding machine manufactured by Sanwa Kogyo Co., Ltd. was used, and the heating setting of the molding machine was 30 V with an upper heater of 200 V × (300 W × 40 heaters = 12 KW) and an output of 30%. , Lower heater 200V × (800W × 6 sheets = 4.8K
W) was set to 40%.

Examples 3 and 4 Except for the amount of the foaming agent shown in Table 2, the same procedure as in Examples 1 and 2 was carried out to form a cylindrical extruded foam into the atmosphere from an annular die attached to the extruder tip. Subsequently, while the inner surface of the cylindrical foam was in a state capable of being press-bonded, the inner surface of the foam was sandwiched by a pressing roll and the inner surface of the foam was bonded to obtain a flat foam. In Examples 2 and 4, an organic peroxide (manufactured by NOF Corporation, Parkmill DM40) was added to 100 parts by weight of the base resin for the purpose of easily obtaining a foam having a small apparent density. It is charged into the first extruder so that the ratio becomes 3 parts by weight,
The melt tension and viscosity of the foamable molten resin were improved.
The foams obtained in Examples 2 and 4 were melted and defoamed by a hot press, and the equilibrium compliance (190 ° C.) was 2.73 × 10 ⁻⁴ Pa ⁻¹ and 2.71 × 10 ⁻⁴ Pa, respectively. It was ^-1 .

The physical properties and the like of the foams obtained in Examples 1 to 4 and Reference Examples 1 and 2 are also shown in Table 2.

[0040]

[Table 2]

Examples 5 and 6 The same resin as in Example 1 and a raw material obtained by mixing talc as a cell regulator were supplied to an extruder having a diameter of 40 mm, and heated.
After kneading to obtain a molten resin, isobutane as a physical foaming agent is press-fitted and kneaded into the resin in the extruder to form a foamable melt.
Filling into a 0 mm accumulator, then injecting the foamable melt from the accumulator, and extruding from a flat die of 3 mm clear and 80 mm long,
A good plate-like extruded foam was obtained. The amount of the foaming agent added, the amount of talc added, and the resin temperature during extrusion foaming are as shown in Table 3.

Example 7 The same procedure as in Example 5 was carried out except that the peroxide was used and the base resin was thickened in the same manner as in Example 2 for the purpose of lowering the open cell ratio of the foam. By doing so, a good plate-like extruded foam was obtained. The amount of the foaming agent added, the amount of talc added, and the resin temperature during extrusion foaming are as shown in Table 3. The equilibrium compliance of the foam obtained in Example 7 melted and defoamed by a hot press was 2.80 × 10 ⁻⁴ Pa ⁻¹ .

Example 8 The same operation as in Example 5 was carried out except that a 2.5 cm square prism die was used, to obtain a good cylindrical extruded foam. The amount of the foaming agent added, the amount of talc added, and the resin temperature during extrusion foaming are as shown in Table 3. Reference Example 3 The same resin as in Reference Example 1 was used. A foam was obtained. The amount of the foaming agent added, the amount of talc added, and the resin temperature during extrusion foaming are as shown in Table 3.

Table 3 also shows the physical properties and the like of the foams obtained in Examples 5 to 8 and Reference Example 3.

[0045]

[Table 3]

The methods for measuring and evaluating the physical properties in Tables 2 and 3 are as follows. [Tensile elongation, tensile modulus and tensile strength of foam] JIS K for extrusion direction (MD) and width direction (TD)
6767 (1976), a dumbbell-shaped No. 1 test piece was prepared, and the test speed was 500 mm using a universal testing machine.
/ Min, JIS K under the conditions of 50 mm between chucks
A tensile rupture test was performed according to the 6767A method. [Compressive strength of foam] Regarding thickness direction JIS K7
220 (1983), and the value at the time of 25% deformation was used as 25% compressive strength. [Compressive modulus of foam] JIS K for thickness direction
7220 (1983). [Open cell ratio] The open cell ratio of the foam was as follows: the apparent volume of the foam: Va (cm ³ ), and the true volume of the foam: Vx (c)
m ³ ), the weight of the foam: W (g), and the density of the base resin of the foam: ρ (g / cm ³ ). The apparent volume of the foam is an apparent volume determined from the outer dimensions of the sample, and the true volume of the foam is independent of the volume of the base resin constituting the foam and the volume of the foam. This is the sum of the bubble volume and the total bubble volume. Therefore, the volume percentage (open cell rate) of the cells that have been made into open cells can be obtained by the following equation (1). Open cell ratio (%) = (Va−Vx) × 100 / (Va−W / ρ) (1) The true volume of the foam is the above sample, ASTM D-2.
According to 856-70 [1976 recertification] (Procedure C), it was determined using an air-comparison hydrometer. [Average bubble diameter] It was determined based on ASTM D3576-77. However, the operation of finally dividing by 0.616 is not performed, the number of bubbles intersecting with the reference line (number) is counted, and the length (mm) of the reference line is calculated by dividing the obtained number of bubbles (number). This is the value obtained from the above. [Apparent density] It was determined based on JIS K7222 (1985). However, the test piece is 50 cm ^{3 in the} JIS.
However, when a test piece of 50 cm ³ or more cannot be cut out, a test piece of less than 50 cm ³ may be used. [Biodegradability] A test piece cut from the obtained foam was buried in soil to conduct a soil degradability test, and those having a weight loss of 70% by weight or more after 30 weeks were evaluated as good.

[0047]

The polyester resin foam of the present invention is
It is excellent in biodegradability, hydrolysis resistance, mechanical properties such as tension, and has excellent properties in flexibility and cushioning that could not be achieved with conventional biodegradable resin foams. It is extremely useful as a packaging material for home appliances, a cushion material and other materials for various uses. Further, the method for producing a polyester resin foam of the present invention,
Equilibrium compliance (J ₀ ) in a dynamic viscoelasticity measurement at 190 ° C. containing a specific polyester copolymer as a main component
Is 1.8 × 10 ⁻⁴ Pa ⁻¹ or more, and the tensile modulus is 100MP.
By extruding and foaming using a resin that is a or less and a foaming agent containing a physical foaming agent, a good foam such as a sheet, a plate, and a rod having excellent cell structure, appearance and physical properties is obtained. be able to. Therefore, it is possible to sufficiently bring out the properties of the base resin having excellent properties,
It can be used more effectively.

[Brief description of the drawings]

FIG. 1 is a graph showing an example of the relationship between creep compliance J (t) and time.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yoshihisa Ishihara 10-3 Satsukicho, Kanuma-city, Tochigi Prefecture JSP Kanuma Research Institute, Inc. (72) Inventor Naotochi Kogure 10-3, Satsukicho, Kanuma-shi, Tochigi Inside the JSP Kanuma Research Institute (72) Inventor Seiji Takahashi 10-3 Satsukicho, Kanuma City, Tochigi Prefecture Inside the JSP Kanuma Research Institute, Inc. (72) Inventor Masato Naito 10-3 Satsukicho, Kanuma City, Tochigi Prefecture, Japan F term (reference) 4F074 AA66 AB05 BA37 BA38 CA22 DA02 DA08 DA13 DA23

Claims (11)

[Claims] 1. A polyester copolymer containing terephthalic acid component units and adipic acid component units and / or succinic acid component units as main dicarboxylic acid component units.
% Or more, and an apparent density of a base resin having a tensile modulus of 100 MPa or less is 0.03 to 0.2 g / c.
m ³ , a polyester resin foam having a thickness of 0.3 to 10 mm. 2. A polyester copolymer containing terephthalic acid component units and adipic acid component units and / or succinic acid component units as main dicarboxylic acid component units.
% Or more, and the apparent density of the base resin having a tensile modulus of 100 MPa or less is 0.035 to 0.25 g / c.
m ³ , a polyester-based resin foam having a cross-sectional area perpendicular to the extrusion direction of 5 cm ² or more. 3. The polyester resin foam according to claim 1, wherein the polyester copolymer contains a butanediol component unit as a main diol component unit. 4. The polyester resin foam according to claim 1, wherein the foam has an open cell ratio of 70% or less. 5. The polyester resin foam according to claim 1, wherein the foam has a tensile elongation of 200% or more and a tensile modulus of 1 to 30 MPa. 6. The polyester resin foam according to claim 2, wherein the foam is a plate-like foam having a compressive strength in the thickness direction of 1 to 50 kPa and a compressive elasticity of 0.1 to 6 kPa. 7. The molar ratio of terephthalic acid component units to adipic acid component units and / or succinic acid component units is 20:
The polyester resin foam according to any one of claims 1 to 6, wherein the ratio is 80 to 50:50. 8. A polyester copolymer containing terephthalic acid component units and adipic acid component units and / or succinic acid component units as main dicarboxylic acid component units.
% By weight, and the equilibrium compliance (J ₀ ) determined by dynamic viscoelasticity measurement is at least 1.8 × 10 ⁻⁴ Pa ⁻¹ ,
A resin having a tensile modulus of 100 MPa or less and a foaming agent containing a physical foaming agent are kneaded with an extruder to form a foamable molten resin, and the molten resin is extruded from a high-pressure region to a low-pressure region to foam. A method for producing a polyester resin foam, which is characterized in that: 9. An equilibrium compliance (J ₀ ) determined by dynamic viscoelasticity measurement of the resin is 2.0 × 10 ^-4 to 1.10.
The method for producing a polyester resin foam according to claim 8, wherein the pressure is 5 ^10-3 Pa- ¹ . 10. The method for producing a polyester resin foam according to claim 8, wherein the physical foaming agent is an organic physical foaming agent. 11. The method for producing a polyester resin foam according to claim 10, wherein the organic physical foaming agent is normal butane and / or isobutane.